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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_5802_Библиотеки_им_академика_М_И_Перельмана.pdf
Upper abdominal
36
Celiac and superior mesenteric arteries
PREPARATION
Patient should fast for 8–12 hours prior to the examination.
POSITION
Patient supine.
TRANSDUCER
1.0–5.0 MHz curvilinear transducer.
METHOD
Ensure a Doppler beam/vessel angle of ≤ 60°. Locate the level of the
supra-renal aorta in the transverse plane, identifying the celiac artery
(CA) and the superior mesenteric artery (SMA), and then examine in
the longitudinal direction. Use a sample volume of 2 mm. Measure
the peak systolic velocity (PSV) as the sample volume is moved from
the aorta to the proximal arteries. Record the maximum peak systolic
velocity.
APPEARANCE
Best seen in the longitudinal view, where the CA and SMAs arise from
the anterior aspect of the aorta, in close proximity to each other. Only
high-grade mesenteric artery stenosis (≥ 70%) are likely to be symptomatic.
MEASUREMENTS
PSVs show a higher overall accuracy than end diastolic velocity (EDV).
Superior mesenteric
artery PSV (cm/s)
Normal 125 ± 25 123 ± 27
Stenosis ≥ 50% 295 240
Stenosis ≥ 70% 400 320
FURTHER READING
AbuRahma AF, Stone PA, Srivastava M, Dean LS Keiffer T
Hass SM, Mousa AY. Mesenteric/celiac duplex ultrasound
interpretation criteria revisited. J Vascular Surg. 2012;
55:428–436.
Celiac axis PSV
(cm/s)
Celiac and superior mesenteric arteries
Peak systolic velocity in the proximal SMA. Angle correction is imprecise in the proximal
SMA if there is signicant curvature.
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High velocities in the CA origin indicate a severe stenosis.
Upper abdominal
38
Doppler ultrasound measurement of
post-prandial intestinal blood ow
PREPARATION
Patient should fast overnight, and the examination should be performed after 30 minutes of supine rest.
POSITION
Patient supine with head of bed elevated 30°.
TRANSDUCER
1.0–5.0 MHz curvilinear transducer.
METHOD
Superior mesenteric and celiac arteries can be identied either longitudinally or transversely. The angle of insonation should be kept at
≤ 60° and the vessels examined along their visible length. The following parameters may be measured: peak systolic velocity (PSV), end
diastolic velocity (EDV), and the pulsatility index (PI). A “standard”
800kcal meal is consumed and serial Doppler measurements are made
over the following hour.
Peak Systolic Velocity – End Diastolic Velocity
PI =
Time averaged maximum velocity
APPEARANCE
Best seen in the longitudinal view, where the celiac axis and superior
mesenteric arteries arise from the anterior aspect of the aorta, in close
proximity to each other.
MEASUREMENTS
Pre-meal Post-meal
Superior mesenteric artery
PSV EDV PI PSV EDV PI
Normal 100 cm/s 16 cm/s 3.6 154 cm/s 46 cm/s 1.8
Celiac axis
Normal 120 cm/s 30 cm/s 1.5 130 cm/s 40 cm/s 1.5
Doppler ultrasound measurement of post-prandial intestinal blood ow
The superior mesenteric
artery spectral Doppler
waveform in a fasting
patient.
39
The spectral Doppler
waveform has altered
following a meal, with
a high forward diastolic
component.
A meal should cause an increase in both systolic and diastolic velocities and a reduction in the PI, indicative of a fall in distal mesenteric
vascular impedance. The increase in superior mesenteric artery EDV
can be between 150% and 300%. Changes in the celiac artery are less
noticeable as the bulk of celiac blood ow is not to the gut.
FURTHER READING
Muller AF, Role of duplex Doppler ultrasound in the assessment
of patients with postprandial abdominal pain. Gut. 1992;
33:460–465.
Upper abdominal
40
Inferior mesenteric artery
PREPARATION
Patient should fast overnight.
POSITION
Supine.
TRANSDUCER
1.0–5.0 MHz curvilinear transducer or 3–8 MHz linear array transducer.
METHOD
The inferior mesenteric artery (IMA) is identied arising from the aorta
anteriorly and to the left. Spectral Doppler waveforms are obtained
from the proximal 3–4 cm of the artery along its longitudinal axis
(Doppler angle ≤ 60°). The IMA is seen in 92% of subjects.
APPEARANCE
Tubular structure arising from the aorta.
MEASUREMENTS
The spectral Doppler waveform demonstrates pulsatile ow that may
be triphasic. Stenosis of the IMA is diagnosed by velocity increase.
Normal values
PSV 98 ± 30 cm/s
EDV 11 ± 5 cm/s
Optimum threshold for stenosis ≥ 50%
PSV ≥ 250 cm/s
EDV ≥ 90 cm/s
IMA/Aortic PSV ratio ≥4
Inferior mesenteric artery
A longitudinal image
through the lower aorta
demonstrates the inferior
mesenteric artery.
FURTHER READING
AbuRahma AF, Dean LS. Duplex ultrasound interpretation criteria
for inferior mesenteric arteries. Vascular. 2012; 20: 145–149.
Denys AL, Lafortune M, Aubin B, Burke M, Breton G. Doppler
sonography of the inferior mesenteric artery: A preliminary
study. J Ultrasound Med. 1995; 14:435–439.
Erden A, Yurdakul M, Cumhur T. Doppler waveforms of the
normal and collateralized inferior mesenteric artery. AJR Am J
Roentgeneol. 1998; 171:619–627.
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2
URINARY TRACT
Venus Hedayati, Colin R. Deane,
Keshthra Satchithananda, and
PaulS.Sidhu
Kidneys 44
Evaluation of acute renal
obstruction with intrarenal
Doppler 48
Renal circulation and renal artery 50
Retroperitoneal lymph nodes 54
Bladder 56
Bladder volume and residual
volume 56
Bladder wall 60
Functional bladder imaging 62
Urinary tract
44
Kidneys
PREPARATION
None.
POSITION
Supine, left and right anterior oblique and, if necessary, prone.
TRANSDUCER
2.0–6.0 MHz curvilinear transducer.
Tissue harmonic imaging is often used, particularly in obese patients.
METHOD
Image the right kidney using the liver as an acoustic window. The left
kidney is typically more difcult to visualize. The left anterior oblique
45° or right decubitus position may help, and asking the patient to
suspend respiration ensures less movement. Both kidneys should be
imaged in both longitudinal and transverse planes.
To better visualize the upper poles, ipsilateral arm elevation and deep
inspiration may be useful.
The right kidney lies 1–2 cm lower than the left.
APPEARANCE
The kidneys comprise three main parts: the cortex, the sinus, and the
medulla.
The cortex comprises the bulk of the kidney, and reectivity of the renal
cortex is less than the adjacent spleen on the left and either slightly less
reective or isoechoic to the liver on the right. The renal sinus contains
multiple structures—the pelvis, calyces, vessels, and fat—and is hyperechoic due to the presence of fat. The renal pyramids (medulla) are
poorly dened triangular structures at the outer edge of the renal sinus
at regular junctions with the cortex and are hypo-echoic. The renal
capsule can be identied as a thin, high-reective rim.
MEASUREMENTS
Three measurements can be made and a volume calculated (0.49 ×
Length × Width × Anterior Posterior diameter), although usually, only
a length is required.
Length: Obtained from the sagittal image, measuring the longest cranio-caudal length. This is usually the only quoted measurement in a
report.
Kidneys
A sagittal image with two measurements obtained in the longitudinal and anteroposterior
directions.
45
The width is measured from
a transverse image obtained
through the renal hilum.